37 research outputs found
First 230 GHz VLBI Fringes on 3C 279 using the APEX Telescope
We report about a 230 GHz very long baseline interferometry (VLBI) fringe
finder observation of blazar 3C 279 with the APEX telescope in Chile, the
phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory
(ARO). We installed VLBI equipment and measured the APEX station position to 1
cm accuracy (1 sigma). We then observed 3C 279 on 2012 May 7 in a 5 hour 230
GHz VLBI track with baseline lengths of 2800 M to 7200 M and
a finest fringe spacing of 28.6 micro-arcseconds. Fringes were detected on all
baselines with SNRs of 12 to 55 in 420 s. The correlated flux density on the
longest baseline was ~0.3 Jy/beam, out of a total flux density of 19.8 Jy.
Visibility data suggest an emission region <38 uas in size, and at least two
components, possibly polarized. We find a lower limit of the brightness
temperature of the inner jet region of about 10^10 K. Lastly, we find an upper
limit of 20% on the linear polarization fraction at a fringe spacing of ~38
uas. With APEX the angular resolution of 230 GHz VLBI improves to 28.6 uas.
This allows one to resolve the last-photon ring around the Galactic Center
black hole event horizon, expected to be 40 uas in diameter, and probe radio
jet launching at unprecedented resolution, down to a few gravitational radii in
galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in
detail, follow-up observations with APEX and five other mm-VLBI stations have
been conducted (March 2013) and are being analyzed.Comment: accepted for publication in A&
Georeferenced soil information system: assessment of database
Land-use planning is a decision-making process that
facilitates the allocation of land to different uses that
provide optimal and sustainable benefit. As land-use
is shaped by society–nature interaction, in land-use
planning different components/facets play a significant
role involving soil, water, climate, animal (ruminant/
non-ruminant) and others, including forestry
and the environment needed for survival of mankind.
At times these components are moderated by human
interference. Thus land-use planning being a dynamic
phenomenon is not guided by a single factor, but by a
complex system working simultaneously,which largely
affects the sustainability. To address such issues a
National Agricultural Innovation Project (NAIP) on
‘Georeferenced soil information system for land-use
planning and monitoring soil and land quality for
agriculture’ was undertaken to develop threshold
values of land quality parameters for land-use planning
through quantitative land evaluation and crop
modelling for dominant cropping systems in major
agro-ecological sub-regions (AESRs) representing
rice–wheat cropping system in the Indo-Gangetic
Plains (IGP) and deep-rooted crops in the black
soil regions (BSR). To assess the impact of landuse
change, threshold land quality indicator values
are used. A modified AESR map for agricultural landuse
planning is generated for effective land-use planning
Soil information system: use and potentials in humid and semi-arid tropics
The articles presented in this special section emanated from the researches of consortium members of the National Agricultural Innovative Project (NAIP, Component 4) of the Indian Council of Agricultural Research (ICAR), New Delhi. These researches have helped develop a soil information system (SIS). In view of the changing scenario all over the world, the need of the hour is to get assistance from a host of researchers specialized in soils, crops, geology, geography and information technology to make proper use of the datasets. Equipped with the essential knowledge of data storage and retrieval for management recommendations, these experts should be able to address the issues of land degradation, biodiversity, food security, climate change and ultimately arrive at an appropriate agricultural land-use planning. Moreover, as the natural resource information is an essential prerequisite for monitoring and predicting global environmental change with special reference to climate and land use options, the SIS needs to be a dynamic exercise to accommodate temporal datasets, so that subsequently it should result in the evolution of the soil information technology. The database developed through this NAIP would serve as an example of the usefulness of the Consortium and the research initiative of ICAR involving experts from different fields to find out the potentials of the soils of humid and semi-arid bioclimatic systems of the country
Heat and Mass Transfer by Natural Convection from a Vertical Surface to the Stratified Darcian Fluid
Novolac epoxy resin based inhibition system for composite propellants
34-39<span style="font-size:11.0pt;line-height:115%;
font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:arial;mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">Thirty one compositions based on commercially
available Dobeckot E4, polyamide hardener EH411, polyamine hardener 758,
reactive diluent, Dobeckot C and antimony trioxide filler have been made and studied
in terms of characteristics such as gel time, exotherm peak temperature,
tensile strength, elongation, burning rate, loss in weight, water absorption
and bond strength with composite propellants. Based on important
characteristics, composition 28 has been selected for inhibition of composite
propellants (booster and sustainer mode) and statically evaluated after
conditioning at ambient temperature (+27o C for 24 h), cold (- 40o
C for 20 h) and hot (+ 50o C for 16 h). The <i style="mso-bidi-font-style:
normal">P-t profiles show that the composition 28 is a potential inhibition
system for composite propellants from -40 to + 50o C.</span
Image Acquisition for Biometric: Face Recognition
Biometrics is mostly used for authentication purposes in security. Due to the covid-19 pandemic situation, nowadays distance-based authentication systems are more focused. Face recognition is one of the best approaches which can use for authentication at distance. Face recognition is a challenging task in various environments. For that taking input from the camera is very important for real-time applications. In this chapter, we are more focusing on how to acquire the face image using MATLAB. The complete chapter is divided into five sections introduction, definition of biometrics, image acquisition devices, image acquisition process in MATLAB